Orthodontic appliances and materials

ABSTRACT

An orthodontic appliance shaped to receive teeth. The orthodontic appliance can be constructed from a laminate structure with an outer transparent layer and an inner translucent layer. The translucent layer can scatter light to decrease a relative degree or perceived gloss to the human eye, and hence provide a more natural appearance to the orthodontic appliance.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/820,663, filed on Mar. 16, 2020, which claims the benefit of U.S.Provisional Application No. 62/933,977, filed on Nov. 11, 2019. All ofthe foregoing applications are incorporated by reference.

BACKGROUND

An objective of orthodontics is to move a patient's teeth to positionswhere function and/or aesthetics are optimized. Traditionally,appliances such as braces are applied to a patient's teeth by a treatingpractitioner and the set of braces exerts continual force on the teethand gradually urges them toward their intended positions. Over time andwith a series of clinical visits and reactive adjustments to the bracesby the practitioner, the appliances to move the teeth toward their finaldestination.

More recently, alternatives to conventional orthodontic treatment withtraditional affixed appliances (e.g., braces) have become available. Forexample, systems including a series of molded plastic aligners havebecome commercially available from Align Technology, Inc., San Jose,Calif., under the trade name Invisalign® System. The Invisalign® Systemis described in numerous patents and patent applications assigned toAlign Technology, Inc. including, for example in U.S. Pat. Nos.6,450,807, and 5,975,893. Such aligners are commonly called “clear”aligners due to a transparent plastic construction. Similarlyconstructed (i.e., thicker) clear retainers (e.g. ESSIX retainers) alsoexist as a post-procedure option for orthodontic patients.

Clear aligners and retainers are popular among patients over patientsfor ease of use and aesthetic reasons, as the clear plastic touted asbeing much less noticeable by others. While clear aligners and retainersmay be more aesthetically acceptable to many, such devices are not“invisible.” The devices add an unnatural gloss to the teeth due tolight interactions with the transparent plastic. For some patients, thisgloss effect reduces appliance wear compliance.

SUMMARY OF THE INVENTION

Embodiments of the invention relate to orthodontic appliances andmaterials as summarized in the following paragraphs. Some embodimentsrelate to orthodontic appliances and materials that have a lessnoticeable gloss and a more natural oral appearance. In someembodiments, an appliance can include a white translucent or opaquelayer of material covered by a transparent layer of material.

Some embodiments related to an orthodontic appliance. The orthodonticappliance can be formed from a laminate material shaped to fit overteeth. The laminate material can include a first layer having atransparent material, a second layer having an opaque or translucentmaterial; and a third layer also including the transparent material. Thesecond layer can be between the first and third layer.

In some embodiments, the first and third layer can include at least aportion of polyethylene terephthalate glycol-modified (PETG).

In some embodiments, the second layer can be a translucent material andthe second layer can be at least somewhat crystalized to provide arelative degree of translucency.

In some embodiments, the second layer can include at least a portion ofa polyurethane.

In some embodiments, the second layer can be at least somewhatcrystalized to provide a relative degree of translucency.

In some embodiments, the second layer can be decrystallized duringformation of the orthodontic appliance to determine a degree oftranslucency for the second layer.

In some embodiments, the degree of translucency of the second layer isdependent on how long and/or the amount of heat is applied to thelaminate material during thermoforming.

In some embodiments, the second layer can include at least a portion ofa thermoplastic elastomer, such as a thermoplastic copolyester,

In some embodiments, the second layer can include at least a portion ofa maleic anhydride grafted PE (HDPE).

In some embodiments, the second layer can include at least a portion ofa reactive terpolymer.

In some embodiments, the laminate material can be 0.025-0.045 inchesthick.

Some embodiments relate to an orthodontic appliance material that can bea laminate 0.025-0.045 inches thick and can have a translucent or opaquelayer and at least one transparent layer.

In some embodiments, the orthodontic appliance material can include afirst transparent layer and second transparent layer, and thetranslucent layer can be between the first and second transparent layer.

In some embodiments, the orthodontic appliance material can be sized tofit commercially available orthodontic appliance device.

In some embodiments the first transparent layer and second transparentlayer can each be a transparent copolyester and the translucent oropaque layer can be a thermoplastic copolyester.

In some embodiments, the first transparent layer and second transparentlayer each consist of a transparent polyethylene terephthalateglycol-modified (PETG) and the translucent or opaque layer consists of athermoplastic copolyester (TPC/TPE-E).

Some embodiments relate to an orthodontic appliance material having apolymer laminate 0.025-0.040 inches thick and only including a singletranslucent layer between two transparent layers.

Some embodiments relate to a method for forming an orthodonticappliance. A laminate material can be placed into an orthodonticappliance thermoforming device. The laminate material can include afirst layer of a transparent material; a second layer of a crystallizedthermoplastic elastomer; and a third layer of the transparent material.The second layer can be between the first and third layer. The laminatematerial can be thermoformed into the orthodontic appliance according topressure, heating, and time settings of the orthodontic appliancethermoforming device. At least the heating and time settings can beselected to at least partially decrystallize the thermoplastic elastomerof the second layer so as to make the second layer relatively moretransparent.

In some embodiments, at least the heating and time settings are selectedto at least partially decrystallize the thermoplastic elastomer of thesecond layer so to become translucent.

In some embodiments, increasing an amount of heat energy applied to thelaminate material and/or increasing the amount of time the laminatematerial is heated can cause the second layer to have greater relativetransparency.

In some embodiments, the heating settings can include a setting of 220°C. (427° F.).

In some embodiments, the time setting can include a heating time of30-60 seconds.

In some embodiments, increasing the amount of heat applied to thelaminate material and/or increasing the amount of time the laminatematerial is thermoformed can cause the second layer to increase in anamount of translucency.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of at least certain embodiments, referencewill be made to the following Detailed Description, which is to be readin conjunction with the accompanying drawings.

FIG. 1 is a perspective view of an orthodontic appliance, according tosome embodiments.

FIG. 2A is an exploded view of an orthodontic appliance, according tosome embodiments.

FIG. 2B is a cross-section of a laminate material, according to someembodiments.

FIG. 3 is a perspective view of a process for molding an orthodonticappliance, according to some embodiments.

FIG. 4A is a photograph of a cross-section of a laminate material,according to some embodiments.

FIG. 4B is a photograph of the laminate material of FIG. 4A formed intoan orthodontic appliance, according to some embodiments.

The figures depict various embodiments of the present invention forpurposes of illustration only, wherein the figures use like referencenumerals to identify like elements. One skilled in the art will readilyrecognize from the following discussion that alternative embodiments ofthe structures and methods illustrated in the figures may be employedwithout departing from the principles of the invention described herein.

DETAILED DESCRIPTION

Embodiments are disclosed that relate to orthodontic appliancesconstructed from multiple shells for the purpose of maximizing workingelasticity, which is defined herein as the capability of an orthodonticappliance to elastically deform to attach to an initial location of theteeth.

Before the present invention is described in greater detail, it is to beunderstood that this invention is not limited to particular embodimentsdescribed, as such can, of course, vary. It is also to be understoodthat the terminology used herein is for the purpose of describingparticular embodiments only, and is not intended to be limiting, sincethe scope of the present invention will be limited only by the appendedclaims.

Where a range of values is provided, it is understood that eachintervening value, to the tenth of the unit of the lower limit unlessthe context clearly dictates otherwise, between the upper and lowerlimit of that range and any other stated or intervening value in thatstated range, is encompassed within the invention. The upper and lowerlimits of these smaller ranges can independently be included in thesmaller ranges and are also encompassed within the invention, subject toany specifically excluded limit in the stated range. Where the statedrange includes one or both of the limits, ranges excluding either orboth of those included limits are also included in the invention.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although any methods andmaterials similar or equivalent to those described herein can also beused in the practice or testing of the present invention, representativeillustrative methods and materials are now described.

It is noted that, as used herein and in the appended claims, thesingular forms “a”, “an”, and “the” include plural referents unless thecontext clearly dictates otherwise. It is further noted that the claimsmay be drafted to exclude any optional element. As such, this statementis intended to serve as antecedent basis for use of such exclusiveterminology as “solely,” “only” and the like in connection with therecitation of claim elements, or use of a “negative” limitation.

As will be apparent to those of skill in the art upon reading thisdisclosure, each of the individual embodiments described and illustratedherein has discrete components and features which can be readilyseparated from or combined with the features of any of the other severalembodiments without departing from the scope or spirit of the presentinvention. Any recited method can be carried out in the order of eventsrecited or in any other order that is logically possible.

FIG. 1 illustrates orthodontic appliance 10, which can be worn by apatient in order to achieve an incremental repositioning of individualteeth or for the purpose of retaining position of moved teeth aftercompletion of an orthodontic treatment (i.e., a “retainer”). In someembodiments, orthodontic appliance 10 can be formed from a laminate ofsuitable layers of polymeric material. Orthodontic appliance 10 can fitover all teeth present in an upper or lower jaw, or less than all of theteeth.

In some embodiments, only certain teeth received by an appliance will berepositioned by the appliance while other teeth can provide a base oranchor region for holding the appliance in place as it applies forceagainst the tooth or teeth targeted for repositioning. In some cases,many or most, and even all, of the teeth will be repositioned at somepoint during treatment. Teeth that are moved can also serve as a base oranchor for holding the appliance as it is worn by the patient.Typically, no wires or other means will be provided for holding anappliance in place over the teeth. In some cases, however, it may bedesirable or necessary to provide individual anchors on teeth withcorresponding receptacles or apertures in the appliance so that theappliance can apply a selected force on the tooth. Basic methods fordetermining an orthodontic treatment plan using a series of incrementedappliances as well as instructions for molding orthodontic appliancesare well known, and, for example, are described in U.S. Pat. Nos.6,450,807, and 5,975,893, which are incorporated by reference herein,but only to an extent that those references do not contradict the newerteachings disclosed herein.

An appliance can be designed and/or provided as part of a set of aplurality of appliances. In such an embodiment, each appliance may beconfigured so a tooth-receiving cavity has a geometry corresponding toan intermediate or final tooth arrangement intended for the appliance.The patient's teeth can be progressively repositioned from an initialtooth arrangement to a target tooth arrangement by placing a series ofincremental position adjustment appliances over the patient's teeth. Atarget tooth arrangement can be a planned final tooth arrangementselected for the patient's teeth at the end of all planned orthodontictreatment. Alternatively, a target arrangement can be one of manyintermediate arrangements for the patient's teeth during the course oforthodontic treatment. As such, it is understood that a target tootharrangement can be any planned resulting arrangement for the patient'steeth that follows one or more incremental repositioning stages.Likewise, an initial tooth arrangement can be any initial arrangementfor the patient's teeth that is followed by one or more incrementalrepositioning stages.

The orthodontic appliances can be generated all at the same stage or insets or batches, e.g., at the beginning of a stage of the treatment, andthe patient wears each appliance until the pressure of each appliance onthe teeth can no longer be felt or has resulted in the maximum amount ofexpressed tooth movement for that given stage. A plurality of differentappliances (e.g., set) can be designed and even fabricated prior to thepatient wearing any appliance of the plurality. After wearing anappliance for an appropriate period of time, the patient replaces thecurrent appliance with the next appliance in the series until no moreappliances remain. The orthodontic appliances are generally not affixedto the teeth and the patient may place and replace the appliances at anytime during the procedure (e.g., patient-removable appliances).

FIG. 2A shows an exploded view of orthodontic appliance 10. Theorthodontic appliance 10 can include a first layer 14 having a teethengaging surface, a second layer 16 over the first layer and a thirdlayer 18 having an outer surface that is exposed to the oral cavity. Insome embodiments, one or more additional layers can be located betweenthe first layer 14 and the second layer 16 and/or between second layer16 and third layer 18.

In some embodiments, third layer 18 is not included and therefore onlyfirst layer 14 and second layer 16 are included, with second layer 16being the tooth engaging layer.

While the orthodontic appliance 10 is shown in an exploded view for thepurpose of better understanding, the layers of the orthodontic appliance10 are intended to be of a single sheet of laminate material. Across-section of laminate material 20 is shown at FIG. 2B. Laminatematerial 20 can be formed as a co-extruded or co-laminated sheet.

Scientific theory of human perception of gloss is complex and evolving.One study found that six types of perceived gloss, i.e., glossperceptions, exist: 1. specular gloss (i.e., perceived shininess,perceived brilliance of highlights); 2. Sheen at grazing angles, whichis the perceived gloss at grazing angles of otherwise matte surfaces; 3.Contrast gloss, which is identified by contrasts between specularitiesand the rest of a surface (i.e., observed contrast between specularhighlights and otherwise diffusely reflecting surface areas); 4.Haze—this is the presence of a hazy or milky appearance adjacent toreflected highlights (e.g. haze surrounding a reflected highlight on abrushed metal surface); 5. Distinctness-of-reflected-image gloss—(i.e.,the perceived distinctness and sharpness of a pseudoimage seen reflectedin a surface); and 6. Absence-of-surface-texture gloss—this is theperceived smoothness of a surface, where non-uniformities of surfacetexture such as blemishes are not visible. See Chadwick et al., “Theperception of gloss: A review.” Vision Research, Vol. 109, Part B, April2015, Pages 221-235. See also Luo et al., “Assessing Gloss of Toothusing Digital Imaging.” Conference on Colour in Graphics, Imaging, andVision, CGIV 2008 Final Program and Proceedings, pp. 307-311. Thesepublications are incorporated by reference. Accordingly, the presence ofdifferent types of gloss perceptions (e.g., brilliance next to hazinesswithin a reflected image) on one surface can result in a high perceptionof gloss.

Accordingly, aspects that contribute to perceived gloss of a prior artclear aligner can include (among others): gloss perceptions derived fromlight interaction on the outer surface of the clear material; glossperceptions derived between light interaction between surfaces of theouter and inner surface of the clear material; gloss perceptions derivedfrom light interaction with trapped saliva between the aligner and thetooth surface; perceptions derived from light interaction with air gapsbetween the aligner and the tooth surface; and gloss perceptions derivedfrom light interaction at inner and outer surface concavity changes(e.g., inner/outer surface lines at gaps between teeth, gumlines). Putanother way, a prior art clear aligner suffers from disparateappearances of high specular gloss, image reflections, shiny surfaces,and dark contrast at the creases/lines between teeth and gumline. Thethickness of prior art clear appliances (typically 0.030-0.045 inches(0.75-1.00 mm)) contributes to these issues by increasing reflectivedistortion.

Light transmittance is the ratio of light intensity passing through amaterial to the intensity of light received by the specimen.Transmittance is determined by light reflection, absorption, andscattering at the material. A highly transparent material has verylittle absorptive and scattering properties. An opaque materialtransmits little to no light because of high scattering and absorptivequalities. Translucent materials have relatively high transmittanceratios, because of negligible absorption, but greatly scatter thetransmitted light, resulting in a hazy, white appearance. First layer 14and third layer 18 can be transparent and second layer 16 can be atranslucent material or an opaque or nearly opaque material. The resultcan be very visually similar (as perceived by the human eye) to theappearance of natural teeth while mitigating gloss perceptions of priorart clear appliances.

Some embodiments of the invention include one or more transparent layerslaminated over a translucent layer or an opaque layer. Embodiments ofthe invention reduce perceived glossiness by: including a thinnertransparent layer(s) to reduce reflective gloss perceptions derived fromlight interaction between internal transparent surfaces; including athinner transparent layer to reduce gloss perceptions derived from lightinteraction at inner and outer surface concavity changes; including alaminated internal translucent or opaque layer to eliminate glossperceptions derived from reflections of teeth surfaces; including alaminated internal translucent layer to eliminate gloss perceptionsderived from air gaps between the transparent layer and the translucentor opaque layer; including a laminated translucent layer to eliminategloss perceptions derived from light interaction with trapped saliva;and including a thinner transparent layer(s) to reduce gloss perceptionsderived from light interaction at surface changes (i.e., hard surfacelines at gaps between teeth, gumlines).

In some embodiments, one or more of first layer 14, second layer 16, andthird layer 18 can have thicknesses ranging from 0.001-0.040 inches(0.025-1.02 mm) thick. In some embodiments, the total thickness oflaminate material 20 can range from 0.020-0.050 inches (0.51-1.27 mm).In some embodiments, first layer 14, second layer 16, and/or third layer18 are 0.015 inches thick prior to forming (e.g. thermoforming) laminatematerial 20 into appliance 10. In some embodiments, first layer 14,second layer 16, and/or third layer 18 are 0.010 inches thick prior toforming (e.g. thermoforming) laminate material 20 into appliance 10.

In some embodiments, first layer 14, second layer 16, and third layer 18can be constructed from one or polymers such as a polyester, acopolyester, a polycarbonate, a thermoplastic polyurethane, apolypropylene, a polyethylene, a polypropylene and polyethylenecopolymer, an acrylic, a cyclic block copolymer, a polyetheretherketone,a polyamide, a polyethylene terephthalate, a polybutylene terephthalate,a polyetherimide, a polyethersulfone, a polytrimethylene terephthalateor a combination thereof.

In some embodiments, first layer 14 and/or third layer 18 are eachformed from a transparent polymer having low haze, high gloss, hightransparency, high regular transmittance, and high total transmittance.For example, for a 0.010 inch (0.25 mm) sample light transmission valuescan include 0.5-1.5% Haze (ASTM D1003), >80 GU @ 45° (ASTM D2457), >80%transparency (ASTM D1746), >80% regular transmittance (ASTM D1003modified), and/or >80% total transmittance (ASTM D1003 Modified)). Insome embodiments, a transparent copolyester (e.g., Eastar™ copolyester6763) can be used having the following properties: (for a 0.010 inch(0.25 mm) sample: 0.8% Haze (ASTM D1003), 108 GU @ 45° (ASTM D2457), 85%Transparency (ASTM D1746), 89% Regular Transmittance (ASTM D1003Modified), 91% Total Transmittance (ASTM D1003 Modified)).

In some embodiments, first layer 14 and third layer 18 are eachtransparent and formed from one or more polymers. In some embodiments,to provide a long service life when oral appliance 10 is a retainer,first layer 14 and/or third layer 18 are selected from materials havinghigh impact resistance. In some embodiments, first layer 14 and thirdlayer 18 are made primarily or entirely from polyethylene terephthalateglycol-modified (PETG). In some embodiments, first layer 14 and/or thirdlayer 18 are made primarily or entirely from polycarbonate. In someembodiments, first layer 14 and/or third layer 18 are made primarily orentirely from polymethylmethacrylate (PMMA).

In some embodiments, first layer 14 and/or third layer 18 is processedto reduce or remove hydrophobic properties (e.g., from PETG) that caninduce saliva foaming. In some embodiments, first layer 14 and/or thirdlayer 18 is processed (e.g. rolled) to have a matte outer surface finishto reduce or remove hydrophobic properties. In some embodiments, firstlayer 14 and/or third layer 18 is processed with an acid or a base toreduce or remove hydrophobic properties. In some embodiments, firstlayer 14 and/or third layer 18 are covered with coatings or additionallayers having hydrophilic properties.

In some embodiments, second layer 16 is formed from one or moretranslucent polymers, which can provide a hazed white appearance. Insome embodiments, second layer 16 is primarily or entirely made ofpolyurethane, thermoplastic elastomer such as a thermoplasticcopolyester (TPC/TPE-E) (e.g. Arnitel® EM400/EM460), maleic anhydridegrafted polyethylene (HDPE) (e.g. Westlake Plastics® GB1002), orreactive terpolymer (e.g. Lotader® blends). In some embodiments, secondlayer 16 can be processed to increase crystallinity, thereby increasinglight scattering to reduce transparency, increase translucence andprovide a white or milky appearance. In some embodiments, second layer16 has greater flexibility (e.g., at least 1.5× less flexural modulus)than first layer 14 and/or third layer 18 to provide oral appliance 10with greater flexibility.

In some embodiments, second layer 16 can be an opaque or nearly opaquematerial, such as a polymer having a white colorant (e.g. titaniumdioxide particles) or a metal foil. In some embodiments, a metal foilcan be coated with titanium dioxide to provide a white appearance.

FIG. 3 depicts an example of process 30 for forming an orthodonticappliance. As shown, laminate material 20 can be formed into orthodonticappliance 10. In this example process, orthodontic appliance 10 can beproduced with the use of physical tooth model, or mold, 32. In someembodiments, laminate material 20 is dimensioned (e.g., 120 mm and/or125 mm diameter circle) for ready processing on a commercially availableforming device (e.g., Erkoform®, Erkoform-3dmotion®, Biostar®, MinistarS®, Drufomat Scan®, Drufosmart®, Essix® SelectVac®). Guidelines foroperating such forming devices can be found at Scheu Dental Technology,Biostar Operating Manual, DE/GB/FR/IT/ES/1.000/06/19 G REF PM 0113.01;Scheu Dental Technology, Application booklet for the pressure mouldingtechnique, GB 2.000/07/19 G REF 0111.02; Erkodent, Thermoforming,S15-3106-48; Erkodent, Erkoform 3D, 61-8002-2; Erkodent, Erkoform-3D+Instructions, BA-Erkoform-3d+-anl-EN-04-04-2019, which are incorporatedby reference herein.

Orthodontic appliance 10 can be produced by heating laminate material 20and then vacuum or pressure forming the material over the teeth in thephysical tooth model 32, and then trimming excess material after removalfrom the mold. Accordingly, orthodontic appliance 10 is a directrepresentation of physical tooth model 32.

In some embodiments, second layer 16 of laminate material 20 (e.g.thermoplastic copolyester (TPC/TPE-E) (e.g. Arnitel® EM400/460)) isprovided in a crystalized form, such that it appears translucent oropaque prior to thermoforming. Some thermoplastic elastomers allow oneto tune the amount of translucency according to the heating temperatureand/or heating time. Thermoforming laminate material 20 for a sufficientamount of time can modify (i.e., decrystalize) the crystalline structureof second layer 16 to make it translucent, or at least more translucentthan originally provided. The degree of translucence depends on theamount of time laminate material 20 is thermoformed and/or thetemperature applied (i.e. thermoforming machine temperature setting) tolaminate material, the thickness of second layer 16, and the thicknessof first layer 14 and third layer 18.

It has been determined that heating times of 30-60 seconds using aBiostar thermoforming device (with thermoforming settings 6 bar/87 psi,427° F.) on laminates with first layer 14 and third layer 18 rangingfrom 0.010-0.015 in. thick and second layer 16 being 0.010 in. thickprovided a good translucency for orthodontic retainers resembling humanteeth. The ability to tune translucence (for oral appliances using atleast one thermoplastic elastomer layer) can be advantageous overappliances that use colorants such TiO2 or BaSO4 or using materials suchas crystallized polyethylene and polypropylene, which, for the purposesof thermoforming an appliance, the degree of possible translucency oropaqueness are more or less set when such materials are formed.

In some embodiments, an oral appliance can be constructed from alaminate shaped to fit in a commercially available thermoforming deviceand has an optimal thickness of 0.020-0.045 inches (prior tothermoforming). In some embodiments, first layer 14 and third layer 18can each be formed from a transparent copolyester (e.g., PETG such asEastar™ copolyester 6763) having an optimal thickness of 0.005-0.020inches (prior to thermoforming), and a second layer 16 being formed froma thermoplastic elastomer (e.g. TPC/TPE-E such as Arnitel® EM400) havingan optimal thickness of 0.005-0.020 inches (prior to thermoforming).

As shown in FIGS. 4A and 4B, in some embodiments, laminate material 20can be thermoformed into a retainer 10 having an optimal thickness of0.040 inches (prior to thermoforming), where first layer 14 and thirdlayer 18 can each be formed from a transparent copolyester (e.g., PETGsuch as Eastar™ 6763) having an optimal thickness of 0.015 inches (priorto thermoforming), and a second layer 16 being formed from athermoplastic copolyester (TPC/TPE-E) (e.g. Arnitel® EM400) having anoptimal thickness of 0.010 inches (prior to thermoforming). As shown inthe photograph of a cross-section of laminate material 20 at FIG. 4A,second layer 16 is opaque prior to thermoforming. Compare with retainer10 of FIG. 4B, in which heating laminate material 20 during athermoforming process causes second layer 16 to decrystallize to adegree from an opaque state to become translucent or have relativelygreater transparency. As described above, the degree of crystallinitycan be tuned to increase or decrease relative translucency of secondlayer 16 and hence retainer 10. It has been determined that usinglaminate material 20 with a commercially available Biostar®thermoforming device with a heating setting of 220° C./427° F., heatingtime of 45-50 seconds, and cooling time of 100-140 seconds or 120seconds provides the level of translucency (or closely similar) ofretainer 10 shown at FIG. 4B. Increasing the heating time will providegreater transparency for retainer 10 via greater relativedecrystallization of second layer 16, and conversely decreasing theheating time will provide less transparency for retainer 10 via lessrelative decrystallization of second layer 16. In some embodiments, thelaminate can be thermoformed into an aligner having an optimal thicknessof 0.030 inches (prior to thermoforming), where first layer 14 and thirdlayer can each being formed from a transparent copolyester (e.g.,Eastar™ copolyester 6763) having an optimal thickness of 0.010 inches(prior to thermoforming), and a second layer 16 being formed from athermoplastic copolyester (e.g. Arnitel® EM400) having an optimalthickness of 0.010 inches (prior to thermoforming).

Throughout the foregoing description, and for the purposes ofexplanation, numerous specific details are set forth in order to providea thorough understanding of the described techniques. It will beapparent, however, to one skilled in the art that these techniques canbe practiced without some of these specific details. Although variousembodiments that incorporate these teachings have been shown anddescribed in detail, those skilled in the art could readily devise manyother varied embodiments or mechanisms to incorporate these techniques.Also, embodiments can include various operations as set forth above,fewer operations, or more operations; or operations in an order.Accordingly, the scope and spirit of the invention should be judged interms of the claims, which follow as well as the legal equivalentsthereof.

What is claimed is:
 1. An orthodontic appliance comprising: a laminatematerial shaped to fit over teeth, wherein the laminate material has atranslucent appearance similar to a color and gloss of natural teeth andcomprises: a first layer comprising a first thermoplastic material, thefirst thermoplastic material alone having a transparent appearance; asecond layer contacting the first layer and comprising a secondthermoplastic material, the second thermoplastic material having atranslucent appearance and a structure that is partially crystalized toprovide the translucent appearance; and a third layer contacting thesecond layer and comprising the first thermoplastic material, whereinthe second layer is between the first and third layer.
 2. Theorthodontic appliance material of claim 1, wherein the secondthermoplastic material comprises a thermoplastic copolyester.
 3. Theorthodontic appliance material of claim 1, wherein a relative degree oftranslucency of the second thermoplastic material is based on a degreeof the structure of the second thermoplastic material beingcrystallized.
 4. An orthodontic appliance material comprising: alaminate material dimensioned for processing on a commercially availablethermo forming device for forming orthodontic aligners, wherein thelaminate material comprises: a first layer comprising a transparentthermoplastic material; a second layer contacting the first layer andcomprising a non-transparent thermoplastic material with a crystalizedstructure, which provides an opaque appearance prior to thermoforming;and a third layer contacting the second layer and comprising thetransparent thermoplastic material, wherein the second layer is betweenthe first and third layer.
 5. The orthodontic appliance material ofclaim 4, wherein the non-transparent thermoplastic material isconfigured to de-crystalize when being thermoformed by the commerciallyavailable thermoforming device to provide a translucent appearance tothe laminate material that is similar to a color and gloss of naturalteeth.
 6. The orthodontic appliance material of claim 5, wherein thenon-transparent thermoplastic material is configured to de-crystalizewhen being thermoformed by the commercially available thermoformingdevice at a heat setting of 220° C.
 7. The orthodontic appliancematerial of claim 6, wherein the non-transparent thermoplastic materialcomprises a thermoplastic copolyester.
 8. An orthodontic appliancecomprising: a laminate material shaped to fit over teeth within a mouthcavity, wherein the laminate material has a translucent appearancesimilar to a color and gloss of natural teeth and comprises: a firstlayer comprising a first thermoplastic material and arranged to contactthe teeth, the first thermoplastic material alone having a transparentappearance; a second layer contacting the first layer and comprising asecond thermoplastic material; and a third layer contacting the secondlayer and comprising the first thermoplastic material, wherein thesecond layer is between the first and third layer and the third layer isarranged to be exposed to the mouth cavity, wherein the secondthermoplastic material of the second layer comprises a structurearranged to scatter light passing through the third layer to reduceperceived visual gloss effects from a perspective of a viewer of theorthodontic appliance.
 9. The orthodontic appliance material of claim 8,wherein the structure of the second thermoplastic material comprises acrystalized structure.
 10. The orthodontic appliance material of claim9, wherein the second thermoplastic material comprises a thermoplasticcopolyester.